One tiny comment regarding TP's suggestion - IMHO it's better to avoid
`unittest.mock` in favor of the equivalent `mocker` fixture provided by
`pytest-mock`.
On 2025/07/10 06:30:22 Tzu-ping Chung wrote:
> Personally I dislike things like assert_called_once_with etc. since
they are easy to miss when you scan a test to see what they are trying
to check. An 'assert' keyword stands out (it’s always the first word in
the line), especially with syntax highlighting.
>
> I do agree the proposed Pytest style is arguably less readable. I
offer another syntax.
>
>
> from unittest.mock import call
>
> assert mock_http_run.mock_calls == [
> call(
> endpoint=f"api/v2/accounts/{expected_account_id}/",
> data=None,
> extra_options=None,
> )
> ]
> assert mock_paginate.mock_calls == []
>
>
> To me, this is on par with assert_called_once_with et al. in terms of
readability, and arguably better for test authors since you don’t need
to remember the various function names anymore, but only 'mock_calls'
and the 'call' helper class.
>
> TP
>
>
> > On Jul 9, 2025, at 23:28, Ferruzzi, Dennis
<fe...@amazon.com.INVALID> wrote:
> >
> > I'm a bit late to the party, and really only reiterating what has
already been said, but of the two examples (original and your rewrite, I
prefer the original. I think as a general rule, we tend to use the
assert_called_once, etc with mocks butt he asserts with non-mocked
variables.
> >
> > I am all for more documentation, but I'd have a slight preference
towards keeping the existing structure.
> >
> >
> > - ferruzzi
> >
> >
> > ________________________________
> > From: Kyungjun Lee <ky...@gmail.com>
> > Sent: Tuesday, July 8, 2025 2:13 AM
> > To: dev@airflow.apache.org
> > Subject: RE: [EXT] [DISCUSS] Consistent test assertion style:
pytest-native vs unittest-style
> >
> > CAUTION: This email originated from outside of the organization. Do
not click links or open attachments unless you can confirm the sender
and know the content is safe.
> >
> >
> >
> > AVERTISSEMENT: Ce courrier électronique provient d’un expéditeur
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> >
> >
> >
> > Thank you Ash and Amogh Desai for your insights and explanations.
> > The information you shared has been incredibly helpful and is
contributing
> > a lot to my growth.
> >
> > 2025년 7월 8일 (화) 오후 2:54, Amogh Desai <am...@gmail.com>님이 작성:
> >
> >> Agreed, I personally also find the current way to be easier to
read and in
> >> most
> >> cases we want to assert if "something" was called, irrespective of the
> >> order it was
> >> called in. So the dedicated function based way works well for me.
> >>
> >> If I want to test a order, I'd rather call parts of code that I
want to
> >> test explicitly and assert
> >> on them.
> >>
> >>> This happens because the mock object is not properly recognized
as a mock
> >> instance at type-checking time, which might confuse some contributors,
> >> especially new ones relying on type hints or static analysis tools.
> >>
> >> Regarding this, I'd say you can either cast mocks to their types
as one
> >> way:
> >> `mock_http_run: MagicMock = mock_http_run` -- give or take, or use
> >> `autospec` to make the mock reflect the signature of the object?
Check out:
> >> https://docs.python.org/3/library/unittest.mock.html#autospeccing
> >>
> >> Thanks & Regards,
> >> Amogh Desai
> >>
> >>
> >> On Mon, Jul 7, 2025 at 6:13 PM Ash Berlin-Taylor
<as...@apache.org> wrote:
> >>
> >>> def test_get_account(self, mock_paginate: Mock, mock_http_run: Mocj,
> >>> conn_id, account_id):
> >>>
> >>>
> >>> Might fix that? IDEs in general do not cope well with purest
tests, and
> >>> are missing context on what most of the variables are, be it
> >> parameterised
> >>> values or fixture values, so this isn’t a problem that is unique to
> >> mocks.
> >>>
> >>>> On 7 Jul 2025, at 12:47, Kyungjun Lee <ky...@gmail.com>
> >> wrote:
> >>>>
> >>>> I'd like to follow up on our previous discussion about
pytest-native vs
> >>>> unittest-style assertions.
> >>>>
> >>>> While working on the following test case:
> >>>>
> >>>> ```python
> >>>>
> >>>> @pytest.mark.parametrize(
> >>>> argnames="conn_id, account_id",
> >>>> argvalues=[(ACCOUNT_ID_CONN, None), (NO_ACCOUNT_ID_CONN,
> >> ACCOUNT_ID)],
> >>>> ids=["default_account", "explicit_account"],
> >>>> )
> >>>> @patch.object(DbtCloudHook, "run")
> >>>> @patch.object(DbtCloudHook, "_paginate")
> >>>> def test_get_account(self, mock_paginate, mock_http_run, conn_id,
> >>>> account_id):
> >>>> hook = DbtCloudHook(conn_id)
> >>>> hook.get_account(account_id=account_id)
> >>>>
> >>>> assert hook.method == "GET"
> >>>>
> >>>> _account_id = account_id or DEFAULT_ACCOUNT_ID
> >>>> hook.run.assert_called_once_with(
> >>>> endpoint=f"api/v2/accounts/{_account_id}/", data=None,
> >>>> extra_options=None
> >>>> )
> >>>> hook._paginate.assert_not_called()
> >>>>
> >>>> ```
> >>>>
> >>>> My IDE shows a warning:
> >>>> Cannot find reference 'assert_called_once_with' in 'function'.
> >>>>
> >>>> This happens because the mock object is not properly recognized as a
> >> mock
> >>>> instance at type-checking time, which might confuse some
contributors,
> >>>> especially new ones relying on type hints or static analysis tools.
> >>>>
> >>>> I realized that this aspect of mock handling might be missing
from our
> >>>> previous discussions. I wanted to bring it up as part of the broader
> >>>> conversation about test styles—particularly how we balance
IDE/tooling
> >>>> support with readability and style consistency.
> >>>>
> >>>> Curious to hear your thoughts on this!
> >>>>
> >>>> @ash @potiuk
> >>>>
> >>>> 2025년 7월 6일 (일) 오후 8:09, Kyungjun Lee <ky...@gmail.com>님이
작성:
> >>>>
> >>>>> Thank you @Potiuk for pointing out the intent behind the “one
assert
> >> per
> >>>>> test” principle, and @ash for highlighting how using dedicated mock
> >>> assert
> >>>>> functions can make the code easier to read and understand.
These were
> >>>>> perspectives I hadn’t fully considered, and I really appreciate you
> >>> sharing
> >>>>> them.
> >>>>>
> >>>>> Thanks to your input, I was able to read more materials and
broaden my
> >>>>> thinking on the topic. That said, my original focus was more on the
> >> idea
> >>>>> that sticking to plain assert statements lowers the entry
barrier for
> >>> new
> >>>>> contributors—because they don’t have to learn multiple assertion
> >> styles.
> >>>>>
> >>>>> Still, as @Potiuk mentioned, I’ll put more thought into making the
> >>> testing
> >>>>> guidelines clearer and more concrete—especially since that helps
> >>> AI-based
> >>>>> tools as well 😄
> >>>>>
> >>>>> For reference, here’s one of the articles I read:
> >>>>> https://medium.com/@kentbeck_7670/test-desiderata-94150638a4b3
> >>>>>
> >>>>> Thank you to everyone who took part in this discussion.
> >>>>>
> >>>>> 2025년 7월 6일 (일) 오후 3:42, Ash Berlin-Taylor
<as...@apache.org>님이 작성:
> >>>>>
> >>>>>> I personally find the dedicated functions way easier to read the
> >> intent
> >>>>>> behind, it’s one function/statement vs 3. More so when you
don’t care
> >>> about
> >>>>>> the order of calls, just that something was called (where to
do this
> >>>>>> manually we’d need to reimplement the helper function)
> >>>>>>
> >>>>>> Additionally pytest already rewrites those to have nicer error
> >>> messages,
> >>>>>> but the dedicated mock assert finding are much easier to read the
> >> code
> >>> and
> >>>>>> understand the intent to me, so I’i am for staying with the
dedicated
> >>>>>> assert functions
> >>>>>>
> >>>>>> -ash
> >>>>>>
> >>>>>>> On 5 Jul 2025, at 13:30, Kyungjun Lee <ky...@gmail.com>
> >>> wrote:
> >>>>>>>
> >>>>>>> I’ve learned a lot of things I didn’t know before.
> >>>>>>> Thank you so much for all your help — I really appreciate it.
> >>>>>>> I’ll get started on this right away!
> >>>>>>>
> >>>>>>> 2025년 7월 5일 (토) 오후 9:18, Jarek Potiuk
<ja...@potiuk.com>님이 작성:
> >>>>>>>
> >>>>>>>>> Haha ... I'm curious — which part sounded like ChatGPT style?
> >>>>>>>> English isn't my first language, so I did get a little help from
> >> it.
> >>>>>>>>
> >>>>>>>> That whole paragraph :) .
> >>>>>>>>
> >>>>>>>>>> Sure! Since you asked for how the test *should* be written, I
> >> took
> >>>>>> the
> >>>>>>>> opportunity to clean it up using a more pytest-native style
while
> >>> also
> >>>>>>>> fixing the mock order issue.
> >>>>>>>>
> >>>>>>>> "Sure! Since you asked ..." sounds like an AI bot.
> >>>>>>>>
> >>>>>>>>> That got me thinking — what do you think about adding a
guideline
> >>>>>>>> document
> >>>>>>>> for writing tests, similar to how we have a coding style guide?
> >>>>>>>>
> >>>>>>>> Absolutely - we already have some "seed' of it "Writing tests"
> >>>>>> chapter in
> >>>>>>>> contributing guideline, but we could definitely make it more
> >>> detailed.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>
> >>>
> >>
https://github.com/apache/airflow/blob/main/contributing-docs/testing/unit_tests.rst#writing-unit-tests
> >>>>>>>>
> >>>>>>>> And - speaking of AI - this is becoming more and more
important to
> >>>>>> describe
> >>>>>>>> any common rules we have and context - so that using Agentic AI
> >>> yields
> >>>>>>>> better results. Kaxil already added
> >>>>>>>> https://github.com/apache/airflow/blob/main/AGENTS.md which
> >>> describes
> >>>>>>>> context for coding agents lile Codex - and we could improve
it and
> >>> link
> >>>>>>>> more docs from our repo if they get more of our agreed
> >> "conventions"
> >>> -
> >>>>>> then
> >>>>>>>> Agents would get it as context and their generated code would be
> >>>>>> consistent
> >>>>>>>> with what we describe there.
> >>>>>>>>
> >>>>>>>> In a way - I think having a good documentation on processes,
tools
> >>> and
> >>>>>>>> conventions was always something I've been after, but with the
> >>> Agentic
> >>>>>>>> workflows it might significantly boost the quality of generated
> >> code
> >>>>>> if we
> >>>>>>>> have more of those conventions and guidelines described.
> >>>>>>>>
> >>>>>>>> So .... ABSOLUTELY ... the more we describe in there, the
better.
> >> And
> >>>>>> we
> >>>>>>>> have no more excuse that "anyhow no-one reads it" - because the
> >>> coding
> >>>>>>>> agents WILL be reading it and acting accordingly. So I think
this
> >> is
> >>> a
> >>>>>> very
> >>>>>>>> good investment to make.
> >>>>>>>>
> >>>>>>>> J.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>> On Sat, Jul 5, 2025 at 2:07 PM Kyungjun Lee <
> >>> kyungjunlee...@gmail.com
> >>>>>>>
> >>>>>>>>> wrote:
> >>>>>>>>>
> >>>>>>>>> Haha ... I'm curious — which part sounded like ChatGPT style?
> >>>>>>>>> English isn't my first language, so I did get a little help
from
> >> it.
> >>>>>>>>>
> >>>>>>>>> But thank you — I actually learned something new from your
> >> comment!
> >>>>>>>>> That got me thinking — what do you think about adding a
guideline
> >>>>>>>> document
> >>>>>>>>> for writing tests, similar to how we have a coding style
guide? It
> >>>>>> might
> >>>>>>>>> help ensure consistency across the Airflow codebase when it
comes
> >> to
> >>>>>>>>> testing styles as well.
> >>>>>>>>>
> >>>>>>>>> 2025년 7월 5일 (토) 오후 8:52, Jarek Potiuk
<ja...@potiuk.com>님이 작성:
> >>>>>>>>>
> >>>>>>>>>> But of course - i'd love to hear what others think - it's
not a
> >>> "very
> >>>>>>>>>> strong" opinion.
> >>>>>>>>>>
> >>>>>>>>>> On Sat, Jul 5, 2025 at 1:48 PM Jarek Potiuk <ja...@potiuk.com>
> >>>>>> wrote:
> >>>>>>>>>>
> >>>>>>>>>>> Cool. That's what I wanted to see.
> >>>>>>>>>>>
> >>>>>>>>>>> By the way - not that there's anything wrong - but was the
> >> answer
> >>>>>>>>> written
> >>>>>>>>>>> by AI initially ? The first paragraph looks suspiciously like
> >> Chat
> >>>>>>>> GPT
> >>>>>>>>>>> answer :D ?
> >>>>>>>>>>>
> >>>>>>>>>>> Comment from my side: I personally prefer the original style.
> >> It's
> >>>>>>>> more
> >>>>>>>>>>> concise and it is easier to read - you see as if the call was
> >>>>>>>> actually
> >>>>>>>>>>> written down. Also this is quite a bit too many assertions in
> >> the
> >>>>>>>>> second
> >>>>>>>>>>> case and it takes a lot of mental effort to understand what
> >>> actually
> >>>>>>>> is
> >>>>>>>>>>> being asserted.
> >>>>>>>>>>>
> >>>>>>>>>>> There is a "school" of writing unit tests that every test
should
> >>>>>> have
> >>>>>>>>> ONE
> >>>>>>>>>>> assertion only. Always. I think it is a bit extreme, and I do
> >> not
> >>>>>>>>> follow
> >>>>>>>>>> it
> >>>>>>>>>>> myself but I think it is also a kind of good direction to
have
> >> ->
> >>>>>> the
> >>>>>>>>>> fewer
> >>>>>>>>>>> assertions you have in your test, the better (I think).
> >>>>>>>>>>>
> >>>>>>>>>>> I think tests should be mostly optimized for easiness of
reading
> >>> and
> >>>>>>>>>>> understanding what is being tested - and it's just not
that easy
> >>> in
> >>>>>>>> the
> >>>>>>>>>>> second case.
> >>>>>>>>>>>
> >>>>>>>>>>> J.
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> On Sat, Jul 5, 2025 at 1:39 PM Kyungjun Lee <
> >>>>>>>> kyungjunlee...@gmail.com>
> >>>>>>>>>>> wrote:
> >>>>>>>>>>>
> >>>>>>>>>>>> Sure! Since you asked for how the test *should* be
written, I
> >>> took
> >>>>>>>> the
> >>>>>>>>>>>> opportunity to clean it up using a more pytest-native style
> >> while
> >>>>>>>> also
> >>>>>>>>>>>> fixing the mock order issue.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Here’s the updated test:
> >>>>>>>>>>>>
> >>>>>>>>>>>> ```python
> >>>>>>>>>>>>
> >>>>>>>>>>>> @pytest.mark.parametrize(
> >>>>>>>>>>>> argnames="conn_id, account_id",
> >>>>>>>>>>>> argvalues=[(ACCOUNT_ID_CONN, None), (NO_ACCOUNT_ID_CONN,
> >>>>>>>>>> ACCOUNT_ID)],
> >>>>>>>>>>>> ids=["default_account", "explicit_account"],
> >>>>>>>>>>>> )
> >>>>>>>>>>>> @patch.object(DbtCloudHook, "run")
> >>>>>>>>>>>> @patch.object(DbtCloudHook, "_paginate")
> >>>>>>>>>>>> def test_get_account(self, mock_paginate, mock_http_run,
> >> conn_id,
> >>>>>>>>>>>> account_id):
> >>>>>>>>>>>> hook = DbtCloudHook(conn_id)
> >>>>>>>>>>>> hook.get_account(account_id=account_id)
> >>>>>>>>>>>>
> >>>>>>>>>>>> assert hook.method == "GET"
> >>>>>>>>>>>>
> >>>>>>>>>>>> expected_account_id = account_id or DEFAULT_ACCOUNT_ID
> >>>>>>>>>>>>
> >>>>>>>>>>>> assert mock_http_run.call_count == 1
> >>>>>>>>>>>> assert mock_http_run.call_args.args == ()
> >>>>>>>>>>>> assert mock_http_run.call_args.kwargs == {
> >>>>>>>>>>>> "endpoint": f"api/v2/accounts/{expected_account_id}/",
> >>>>>>>>>>>> "data": None,
> >>>>>>>>>>>> "extra_options": None,
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> assert mock_paginate.call_count == 0
> >>>>>>>>>>>>
> >>>>>>>>>>>> ```
> >>>>>>>>>>>> Why I chose this style:
> >>>>>>>>>>>>
> >>>>>>>>>>>> -
> >>>>>>>>>>>>
> >>>>>>>>>>>> *Mock verification using assert*: Instead of
> >>>>>>>>>>>> mock.assert_called_once_with(...), I used call_count and
> >>>>>>>> call_args.
> >>>>>>>>>>>> This
> >>>>>>>>>>>> approach aligns better with pytest’s idioms and produces
> >>> cleaner,
> >>>>>>>>>> more
> >>>>>>>>>>>> readable error messages when assertions fail.
> >>>>>>>>>>>> -
> >>>>>>>>>>>>
> >>>>>>>>>>>> *Explicit verification*: Using call_args.args and
> >>>>>>>> call_args.kwargs
> >>>>>>>>>>>> makes
> >>>>>>>>>>>> the test behavior very explicit, which helps with debugging
> >> and
> >>>>>>>>>>>> understanding the exact calls made.
> >>>>>>>>>>>> -
> >>>>>>>>>>>>
> >>>>>>>>>>>> *Decorator order matching argument order*: As @patch
> >> decorators
> >>>>>>>>> apply
> >>>>>>>>>>>> from the bottom up, the argument order has been corrected to
> >>>>>>>> match
> >>>>>>>>> (
> >>>>>>>>>>>> mock_paginate first, then mock_http_run).
> >>>>>>>>>>>>
> >>>>>>>>>>>> Let me know if you'd like to follow a slightly different
> >>> convention
> >>>>>>>> —
> >>>>>>>>>>>> happy
> >>>>>>>>>>>> to adjust!
> >>>>>>>>>>>>
> >>>>>>>>>>>> I was lu
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